Main Bearings | Crankshaft & Engine Main Bearings

Main bearings form the critical interface between the crankshaft and engine block, supporting the crank through every rotation under load. CBT Auto Parts stocks OEM-quality engine main bearings for diesel and petrol engines, machined to exact tolerances to ensure proper oil clearance. The right crankshaft main bearings are here.

Part of our Engine & Powertrain Parts range alongside crankshafts, connecting rods, rod bearings, and engine rebuild kits, our main bearings include King and Taiho options. We carry specifications for SBC, LS1, BBC, 350, 6.7 Cummins, and 351W platforms. Aftermarket main bearings here meet OEM specifications and suit standard and performance rebuilds. We ship worldwide; orders are dispatched fast.

Main Bearings

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FAQs

1. What is the correct oil clearance for main bearings?

Correct main bearing oil clearance is engine-specific. Most petrol engines specify between 0.001" and 0.003" (0.025 to 0.076 mm), while some diesel engines run tighter tolerances. Always refer to the manufacturer's service specification for the engine being rebuilt rather than applying a generic figure.

2. Can main bearings be reused during an engine rebuild?

Reusing main bearings is not recommended. Even bearings with no visible surface damage have accumulated wear at the overlay layer, and the oil clearance will deviate from specification. Replacing the main bearings is standard practice in any engine rebuild intended to return reliable service life.

3. What is the difference between King and Taiho main bearings?

King bearings use tri-metal construction with a surface overlay designed for performance and high-stress applications, with strong contaminant embeddability. Taiho main bearings are manufactured to OEM specification and are the original supplier for many Japanese and European diesel platforms. Both are quality products; the right choice depends on the application and whether performance specification or direct OEM replacement is the goal.

4. How do I know if I need standard or undersize main bearings?

If the crankshaft journals are at their original factory diameter, standard size bearings are correct. If the crankshaft has been reground, undersize bearings matching the regrind increment are required. Your machinist should document the regrind specification; use that figure to confirm the correct undersize increment before ordering.

5. Does CBT Auto Parts ship main bearings internationally?

Yes. All main bearing orders are dispatched from our warehouse and shipped to destinations worldwide. Orders are processed and fulfilled promptly. Contact us before placing your order for an estimated delivery timeframe to your location.